This is a breaking change. Before, usage looked like this:
```zig
const held = mutex.acquire();
defer held.release();
```
Now it looks like this:
```zig
mutex.lock();
defer mutex.unlock();
```
The `Held` type was an idea to make mutexes slightly safer by making it
more difficult to forget to release an aquired lock. However, this
ultimately caused more problems than it solved, when any data structures
needed to store a held mutex. Simplify everything by reducing the API
down to the primitives: lock() and unlock().
Closes#8051Closes#8246Closes#10105
Over the last year of using std.log in practice, it has become clear to
me that having the current 8 distinct log levels does more harm than
good. It is too subjective which level a given message should have which
makes filtering based on log level weaker as not all messages will have
been assigned the log level one might expect.
Instead, more granular filtering should be achieved by leveraging the
logging scope feature. Filtering based on a combination of scope and log
level should be sufficiently powerful for all use-cases.
Note that the self hosted compiler has already limited itself to 4
distinct log levels for many months and implemented granular filtering
based on both log scope and level. This has worked very well in practice
while working on the self hosted compiler.
We already have a LICENSE file that covers the Zig Standard Library. We
no longer need to remind everyone that the license is MIT in every single
file.
Previously this was introduced to clarify the situation for a fork of
Zig that made Zig's LICENSE file harder to find, and replaced it with
their own license that required annual payments to their company.
However that fork now appears to be dead. So there is no need to
reinforce the copyright notice in every single file.
* std.log: still print error messages in ReleaseSmall builds.
- when start code gets an error code from main, it uses std.log.err
to report the error. this resulted in a test failure because
ReleaseSmall wasn't printing `error: TheErrorCode` when an error
was returned from main. But that seems like it should keep working.
So I changed the std.log defaults. I plan to follow this up with a
proposal to change the names of and reduce the quantity of the
log levels.
* warning emitted when using -femit-h when using stage1 backend; fatal
log message when using -femit-h with self-hosted backend (because the
feature is not yet available)
* fix double `test-cli` build steps in zig's build.zig
* update docgen to use new CLI
* translate-c uses `-x c` and generates a temporary basename with a
`.h` extension. Otherwise clang reports an error.
* --show-builtin implies -fno-emit-bin
* restore the compile error for using an extern "c" function without
putting -lc on the build line. we have to know about the libc
dependency up front.
* Fix ReleaseFast and ReleaseSmall getting swapped when passing the
value to the stage1 backend.
* correct the zig0 CLI usage text.
* update test harness code to the new CLI.
* prefix with the message level
* if the scope is not default, also prefix with the scope
This makes the stack trace test pass, with no changes to the
test case, because errors returned from main() now print
`error: Foo` just like they do in master branch.
The logging functions in std.log don't take a scope parameter anymore,
but use the .default scope. To provide your own scope, use the logging
functions in std.log.scoped(.some_other_scope).
As per nmichaels' suggestion: https://github.com/ziglang/zig/pull/6039#issuecomment-673148971
* Add short documentation to std.log.scoped and std.log.default
* Update the module documentation and example to explain the difference
between using explicit scopes, using a scoped logging namespace, and
using the default namespace
* Add a std.log.scoped function that returns a scoped logging struct
* Add a std.log.default struct that logs using the .default scope
Implementation of daurnimator's proposal:
https://github.com/ziglang/zig/issues/5943#issuecomment-669043489
Note that I named the function "scoped" instead of "scope" so as not to
clash with the scope parameter that is used everywhere; this seemed a
better solution to me than renaming the scope parameter to "s" or
"log_scope" or the like.
std.log provides 8 log levels and corresponding logging functions. It
allows the user to override the logging "backend" by defining root.log
and to override the default log level by defining root.log_level.
Logging functions accept a scope parameter which allows the implementer
of the logging "backend" to filter logging by library as well as level.
Using the standardized syslog [1] log levels ensures that std.log will
be flexible enough to work for as many use-cases as possible. If we were
to stick with only 3/4 log levels, std.log would be insufficient for
large and/or complex projects such as a kernel or display server.
[1]: https://tools.ietf.org/html/rfc5424#section-6.2.1
